Currently, it is known to use power adapters and chargers for charging or powering a variety of electronic devices such as cellular telephones, so-call “smart phones” such as Blackberry devices provided by Research In Motion, Inc., personal data assistants, portable music or DVD players, and other similar devices. These devices typically include an on-board battery, and the chargers provide power to the battery. As used herein, the term “charger” refers to devices that provide a step in power (i.e., step power from an input voltage to an output voltage), convert power (i.e., convert input alternating current (AC) to output direct current (DC)) or both.
The charger generally has two connection points, a first one for receiving power and a second one for conveying power. The first connection point is generally prongs or blades that are inserted into a power outlet for receiving power therefrom which, in the United States, is alternating current power. The charger includes circuitry, generally disposed within a housing, for converting or adapting the input power received by the blades into output power delivered to the ITE device. For instance, the input power may be alternating current of a first voltage (such as 110/120V), and the output power may be direct current of a second, generally lower, voltage such as 5V.
The second connection point provides the output power to the ITE device. Generally speaking, for portable devices, the second connection point includes a connector that is removably connectable with the ITE device.
For most devices, the second connection point is remote from the first connection point. In other words, the charger has the blades connectable with the power outlet and mounted in the housing, the housing including the converter circuitry, and the charger has the connector and an electrical cord connecting the converter circuitry with the connector.
Such a configuration for the charger makes use thereof relatively simple. That is, a user may plug the charger blades into the power outlet of their choice (whether it is behind furniture or some other obstruction), and may leave the connector end in a place that is convenient for connecting and disconnecting the ITE device.
Despite this use being simple for a user, it has its own issues. In particular, the prior art chargers draw current at all times, regardless of being connected to the ITE device or not. This current or power draw is known as phantom load. To be more precise, phantom load is residual power consumption by power devices when not connected to their host electronic device, or when the electronic device is shut off.
Phantom load is becoming a greater issue for the public. Electrical devices that result in the described phantom load are continually increasing in per capita usage, populations increase exponentially, and great portions of the world's population are gaining the discretionary capital that enables the purchase of such devices. Energy is becoming more expensive on a monetary basis, and energy production overwhelmingly has an environmental impact, such as fossil fuel or nuclear energy.
Extensive effort has been and continues to be put into development of energy-efficient devices of all sorts. The “Energy Star” program sponsored by the United States Environmental Protection Agency and the United States Department of Energy is well known, though principally for energy efficiency appliances and building products such as glass doors and windows. In parallel with Energy Star standards efforts, a variety of state and federal laws have been enacted that are directed toward external power-supply products, which includes power devices or chargers for portable electronic devices. The most-recent standard for such portable devices is version 2.0 and is considered a push beyond simply forcing the industry to use power efficient components and layouts, requiring more complex power devices and supplies.
A recent development that arose during the preparation of the present application is a prototype device from Nokia that operates with a mechanical switch. Specifically, the Nokia device has a housing end receivable in a power receptacle and including internal circuitry for the charger/adapter functions. A button is located on the housing for turning the Nokia device on, and the circuitry automatically turns off by releasing the button.
While it is believed to have been developed after conception of the invention of present application, the Nokia device highlights some interesting points about efforts in this arena. For instance, the button of the Nokia device is a mechanical button and requires some type of mechanism for releasing the button for the “off” state. The button is also located on a housing for the internal circuitry that is separate from the electronic device connector, the connector being a two-terminal device (that is, having “+” and “−” terminals). The Nokia device also requires some type of mechanism for determining when the device should be shut down.
Most people do not bother to unplug a charger when the charged portable electronic device is removed therefrom. The Nokia device certainly relieves a user from such a burden in order to cut power, but it still requires the user to reach to wherever the device is received in a receptacle in order to turn on the device, such as behind a piece of furniture.
In order to be a true “zero-energy” device, the power input (i.e., AC input) to the power device itself must be cut. Therefore, the location within the circuit at which the power is cut is central. In other words, a switch that merely cuts the output power from the connector (such as might be used to prevent overcharging of a battery) while the converter/adapter circuitry remains under power is not a “zero-energy” device because the internal circuitry is allowed to draw power, the effect being no different than simply removing the electronic device itself. Towards this end, the Nokia device displays a uniform manner of thinking in the industry: a switch for connecting or disconnecting the AC power must be co-located with or closely proximate to the AC input such as the power prongs.
The switch/converter circuitry co-location paradigm demonstrates itself in industry practice and standards, particular as to how such relate to safety. As background, an isolation switch is one that cuts power to a portion of a device or circuit (more appropriately, sub-circuit) in a manner that is sufficient to allow a person to work on that portion of the device without a safety issue. An isolation switch is one that complete cuts power and voltage, etc., from a circuit so that there is zero risk of shock from contact with that circuit. A functional switch is one that, while cutting power, may still allow voltage to be present in a circuit and, thus, a shock may occur from a person coming into contact with the circuit.
A commonly used and well-known standards and approval organization is Underwriters Laboratories (UL), which has a UL 60950-1 standard for direct plug-in power supply (DPIU) devices that states, in section 3.4.5, “isolating switches shall not be fitted in flexible cords.” More broadly, this standard says a “disconnect device shall be provided to disconnect the equipment from the mains supply for servicing,” section 3.4.1, and such “disconnect devices . . . shall be connected as closely as practicable to the incoming supply.” Furthermore, it is stated that “Functional switches are permitted to serve as disconnect devices provided that they comply with all the requirements for disconnect devices. However, these requirements do not apply to functional switches where other means of isolation are provided.” Generally speaking, a switch for a charger (the switch connecting/disconnecting AC or converted DC power) in a cable may be considered a functional switch if the disconnect device is the AC plug for the charger.
Beyond portable electrical devices with removable power chargers for charging the battery thereof, there are many devices which draw a current regardless of their use. For instance, while some devices such as video cassette recorders (VCRs) typically include a clock, many people do not even bother to set said clock, let alone rely upon such as a timepiece.
Accordingly, it is desirable and there is a need for an improved power device, charger or otherwise, for reducing phantom load when a portable electrical device is disconnected from the power device or otherwise not intended to be drawing power from the power device. It is also desirable to provide a device that allows disconnection of power to an electrical device, the electrical device continuing to utilize its manufacturer-supplied power cord.